2.4.6- trichlorobenzoyl chlorid

Use of 2,4,6-trichlorobenzoyl chloride, Et3N, and DMAP, known as the Yamaguchi method,128 is frequently used to effect macrolactonization. The reaction is believed to involve formation of the mixed anhydride with the aroyl chloride, which then forms an acyl pyridinium ion on reaction with DMAP.129... 

Scheme 5 Completion of Thomas synthesis of lb. Reagents and conditions a 2,4,6-tri-chlorobenzoyl chloride, DMAP, CH2CI2, rt, 63% b HCl, EtOH, 40 to 50°C c B0C2O, Et3N, 80% from 29, d H2, Pd/C, EtOH e (i) 2,4,6-trichlorobenzoyl chloride, Et3N, rt, (ii) DMAP, rt, 25% from 30 f TEA, CH2CI2, rt, 82% g CH2O, NaBH3CN, HOAc, 60%...

Scheme 17 Completion of Kang s synthesis of lb. Reagents and conditions a (i) 103,2,4,6-trichlorobenzoyl chloride, Et3N, THF, rt, (ii) 109, DMAP, benzene, rt, 90% b BU4NF, THF, rt, 94% c TEMPO, NaCl02, NaH2P04 buffer (pH 6.7),NaOCl,MeCN,rt,91% d (i) 2,2 -dipyridyl disulfide, Ph3P, MeCN, (ii) CuBr2, MeCN, rt, 62% e (i) H2,10% Pd/C, MeOH, rt, (ii) aq. CH2O, HOAc, rt, 89%...

Esterification using 2,4,6-trichlorobenzoyl chloride (the Yamaguchi reagent). 

Scheme 1 a 2,4,6-trichlorobenzoyl chloride, f-Pr2NEt, THE, then DMAP, benzene, 68%... 

A novel cysteine derivative, spongiacysteine, was isolated recently from marine sponge. It was converted to lactone 4 by reaction with 2,4,6-trichlorobenzoyl chloride, 4-dimethylaminopyridine (DMAP), and triethylamine. Selected nuclear Overhauser enhancement spectroscopy (NOESY) correlation and coupling constants are given <2004CL1262>. 

Trichlorobenzoyl chloride, 552 Trichloroethylene, 552-553 Trichloroiodosilane, 466 Trichloromethylarenes, 119 Trichloro methyl)silane, 553 Trichlorosilane-Triethylamine, 553-544 Tricholomic acid, 188 Triethoxysilane, 554... 

The Yamaguchi Esterification allows the mild synthesis of highly functionalized esters. After formation of a mixed anhydride between the Yamaguchi Reagent (2,4,6-trichlorobenzoyl chloride) and the carboxylic acid, the volatiles are removed and the reaction of the anhydride with an alcohol in presence of a stoichiometric amount of DMAP generates the desired ester. 

Trichlorobenzoyl-chloride, /Pr2EtN, THF, then DMAP, toluene, reflux, 24 h... 

Macrolactonization.1 High dilution is usually essential for macrolactonization, but the 14-membered lactone, 9-dihydroerythronolide A (3), can be obtained in almost quantitative yield by lactonization of the seco-acid 2 via the mixed anhydride formed with 2,4,6-trichlorobenzoyl chloride (1) with triethylamine and 4-dimethyl-... 

The acylation of carboxylic acids with 2,4,6-trichlorobenzoyl chloride gives mixed anhydrides A (Figure 6.14). Triethylamine must be present in this reaction to scavenge the released HC1. Anhydrides A contain two different acyl groups. In principle, both of them could be attacked by a nucleophile. However, one observes the chemoselec-tive attack on the acyl group that originates from the acid used. This is because the... 

Macrolactonizathn with inversion. Lactonization of the optically active seco-acid 1 with P(C sH,), and DEAD followed by hydrolysis of the acetonide group gives the cyclic dilactonc colletodiol (2), formed with inversion of configuration at the hydroxyl-bearing carbon. Lactonization of 1 with 2,4,6-trichlorobenzoyl chloride and tdethylamine (9, 478-479) furnishes 6-epicolletodiol after deprotection. 

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